The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 19, 1998
Filed:
Jul. 22, 1996
Hiroki Nakayama, Kanagawa-ken, JP;
Akihisa Horiuchi, Kanagawa-ken, JP;
Hitoshi Mukaiya, Kanagawa-ken, JP;
Yasunori Murata, Tokyo, JP;
Fumihito Wachi, Kanagawa-ken, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A zoom lens of the rear focus type including, from an object side to an image side, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive refractive power having a stop, and a fourth lens unit of positive refractive power. During zooming from a wide-angle end to a telephoto end, the second lens unit is moved toward the image side, the third lens unit and the stop are moved in unison in a locus convex toward the object side, and the fourth lens unit is moved in a locus convex toward the object side. During focusing, the fourth lens unit is moved, and the following condition is satisfied: -0.3<M3max/.phi..sub.1 <-0.04, where M3max is a maximum value of an amount of axial movement of the third lens unit and the stop from the wide-angle end (a moving direction to the object side being taken as '-'), and .phi..sub.1 is the outer diameter of a frontmost lens of the zoom lens.